In my Scientific American column this month, I wrote about the dawn of the brain–computer interface. Forget about keyboard, mouse, touch screens or even voice recognition: the real dream is thinking about what you want your gadget to do.

BCI (brain–computer interface) has long been a favorite of sci-fi movies (paging Professor Xavier!). However, some early BCI products are already for sale. Unfortunately, this isn't the dawn of BCI—it's the pre-dawn. These products are crude, imprecise and sometimes frustratingly nonresponsive—that's how it goes with EEG-based headsets, which pick up only the faintest electroencephalographic echoes of neural activity through the skull. (Beware, in particular, of the toys, which garner Amazon reviews ranging from wildly polarizing to absolutely scathing.) But these technologies are based on real BCI principles, and when they work, they're a fascinating glimpse of mind–machine merging mergers to come. (Below are representative online prices, such as those found on Amazon.)

Star Wars Science Force Trainer ($35): This toy includes a wireless headset, ping-pong ball and a clear plastic tube with a fan beneath. As you concentrate, your brain activity turns up the fan so that it blows a ping-pong ball up a tube. Yoda's voice guides you: "Reach out with your feelings! Use The Force. Do or do not; there is no try."

Mindflex ($47): Mattel's game is another ball-in-an-air-column setup. This time the object is to guide the ball through hoops, hurdles, funnels and a seesaw. You control the fan power, and therefore the height of the foam ball, with your thoughts; you control the ball's horizontal movement through the course with a knob.

Mindflex Duel ($44): For about the same price, you can buy a two-headset version of the Mindflex. In some games, your concentration controls the fan strength—as in the original game; in others, it controls the lateral movement of the sliding fan, so that you and a buddy can have a kind of "think of war" battle.

Neural Impulse Actuator ($107): This "brain mouse" is marketed as a Windows game-playing accessory that lets you control game functions with your thoughts. You can assign it to trigger left-clicks, for example, or to make your character walk or shoot.

MindSet ($199): This $199 headset, from NeuroSky, is a traditional Bluetooth headset, suitable for Skype calls and so on. But it's also an EEG headset, a somewhat less frivolous one than the games described above. The software includes a simple "brain-wave monitor" app, but the real potential lies in the developer kit, which allows programmers to come up with their own MindSet-driven software.

EPOC ($299): Emotiv's $299 headset is the most serious consumer option yet. The wired headset has 16 contacts, and you're supposed to wet them with saline solution for better contact. As a result, the sensitivity is far superior to what you get from the dry-connection, single-contact headsets. The company includes a few starter games and monitors to get you going—but here again, the real promise is the software development kit.

In short, most of the consumer BCI offerings so far fall under the headings "Gimmick" and "Quick Novelty Wear-Off Factor." But sometimes it's not about how well the bear dances—it's that the bear can dance at all.

Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www.springernature.com/us). Scientific American maintains a strict policy of editorial independence in reporting developments in science to our readers.